DNAm age (DNA methylation age, epigenetic age) is an estimate of biological age from the level of DNA methylation. The term most often refers to Steve Horvath's first epigenetic clock (2013).
The Horvath clock uses 353 CpG sites and works across different tissues, predicting calendar age with a median error of about 3.6 years (correlation r≈0.96).
The Horvath and Hannum clocks
The term DNAm age most often refers to Steve Horvath's clock (2013): it uses 353 CpG sites, was trained on 8,000 samples from 51 tissue types and works across different tissues without adjustments. At the same time Hannum's clock appeared (71 sites, blood). Both models belong to the first generation — they were trained to predict calendar age.
DNAm age and age acceleration
The difference between DNAm age and chronological age is called epigenetic age acceleration. A positive value is associated with increased mortality. On the foundation of these clocks the second generation was later built — PhenoAge and GrimAge.
Limitations
Because the first clocks were trained on calendar age rather than on health, they predict disease and death more weakly than the second-generation clocks. The result depends on the tissue and the laboratory. It is a research, not a diagnostic, tool.
Calculate using this marker
Calculators where DNAm Age is used directly:
Frequently asked questions
How does DNAm age differ from PhenoAge and GrimAge?
DNAm age (first-generation clocks) is trained to predict calendar age. PhenoAge and GrimAge are trained on health and mortality measures, so they predict disease and the risk of death better.
How accurate is the Horvath clock?
It predicts calendar age with a median error of about 3.6 years and a correlation of r≈0.96. But an exact match with the calendar is not the same as predicting health.
Related terms
Sources
- Wikipedia — Epigenetic clock (Horvath clock)
- Levine et al. An epigenetic biomarker of aging (Aging, 2018)